1. Technical Field
The present disclosure relates to a semiconductor device and a manufacturing method thereof and particularly to a semiconductor device that includes silicon carbide and a manufacturing method thereof.
2. Description of the Related Art
Silicon carbide (SiC) is a semiconductor material that has a large band gap and higher hardness compared to silicon (Si). For example, SiC has been applied to power devices such as switching devices and rectifier devices. The power device that uses SiC has an advantage of reducing power loss compared to a power device that uses Si, for example.
Representative semiconductor devices that use SiC are a metal-insulator-semiconductor field-effect transistor (MISFET) and a Schottky-barrier diode (SBD). A metal-oxide-semiconductor field-effect transistor (MOSFET) is one kind of MISFET. Further, a junction-barrier Schottky-barrier diode (JBS) is one kind of SBD.
A discussion has been held that an SiC-MISFET is used as the switching device used for a power converter or the like that drives and controls a load of a motor or the like, for example. In a case where the MISFET is used as the switching device of the power converter, there is a case where a return current flows in the power converter when the MISFET is in an OFF state. In a common inverter circuit, a free-wheeling diode is externally connected with the MISFET in an anti-parallel manner, and the free-wheeling diode thereby becomes a path of the return current. In a case where an SiC-FET is applied to the inverter circuit, the Schottky-barrier diode formed of SiC is selected as the free-wheeling diode.
However, in a case where each of a transistor and a diode that functions as the free-wheeling diode is formed with an independent semiconductor chip, a mounting area may increase in response to an increase in the total number of chips. Further, because inter-chip wiring increases, a parasitic inductance may increase, and noise may occur. Thus, a configuration has been suggested that the transistor and the diode are formed in a single semiconductor chip. Herein, the transistor in such a configuration will be referred to as “transistor with a build-in diode”.
International Publication No. 2007/013367 by the inventor discloses an example where diode cells that have a Schottky electrode are arranged along an outer periphery in which plural transistor cells are formed in a field effect transistor that uses SiC, for example, in the SiC-MISFET. In this example, the Schottky-barrier diode connected with the MISFET in an anti-parallel manner may be formed in the chip, and the semiconductor chip that has both of a switching function of the MISFET and a function of the free-wheeling diode may thus be obtained.